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Project

Towards Integrated Multi-sensor Array Chip for Bioprocess Monitoring

Effective and continuous monitoring of bioprocesses requires simultaneous screening of multiple key parameters to enhance processes and improve product quality. To achieve this, there is a growing interest in miniaturization and sensor parallelization, allowing for in-situ monitoring of lab-scale fermentation baths. This study describes the development and characterization of a microfabricated multi-sensor array chip for monitoring yeast fermentation. The integration of platinum nanostructures (nano-Pt) onto microelectrodes using a simple, scalable electrodeposition procedure resulted in highly sensitive and selective microsensors with minimal measurement variability. The chip incorporates various sensors, including potentiometric parallel-plate nanostructured electrodes for pH measurement, interdigitated nano-Pt electrodes for indirectly assessing microbial growth and activity through electrolyte conductivity, and nano-Pt-based microelectrodes for amperometric monitoring of dissolved oxygen and glucose levels. On-chip reference electrodes eliminate the need for external conventional references, enabling standalone measurements. Additionally, the chip includes a thin-film resistance temperature detector for temperature monitoring. The results demonstrate stable measurements using the on-chip silver|silver chloride (Ag|AgCl) reference electrode, crucial for accurate potentiometric sensing. The utilization of template-free electrodeposited nano-Pt oxide improves the sensitivity and linearity of pH sensing compared to bare Pt electrodes. The temperature sensor exhibits a linear response within the range of 10-75°C and correlates well with reference measurements during in-situ temperature monitoring of yeast culture, achieving an accuracy of approximately 0.4°C. The impedance spectroscopy-based interdigitated electrode (IDE) conductivity sensor shows potential for providing insights into microbial growth and activity, particularly when employing nano-Pt IDE. The nano-Pt dissolved oxygen sensors demonstrate improved sensitivity and linearity compared to bare Pt, while the nano-Pt-based glucose sensor (nano-Pt/GOx) remains sensitive to glucose while being unaffected by interfering substances. In testing within yeast fermentation samples, the nano-Pt/GOx electrodes exhibit agreement with a commercial discrete analyzer, and amperometric tests demonstrate reliable operation at +0.3 V, rendering the nano-Pt biosensor a promising candidate for biological sample monitoring. The novelty of this work lies in the development of an integrated sensor system utilizing nano-Pt electrodes, enabling simultaneous detection of pH, dissolved oxygen, cell growth, and glucose in fermentation processes. Nano-Pt offers advantages such as low applied potential, enhanced reproducibility and sensitivity, absence of interference, extended linearity range, and low power consumption. The chip's versatility allows for accommodating additional sensing sites tailored to specific requirements, such as aroma detection. Its compact size facilitates autonomous mini-capsule usage, making it ideal for real-time bioprocess monitoring. Future efforts will focus on anti-fouling coatings, sterilization strategies, and integrated electronics to enable simultaneous and continuous in-situ monitoring of fermentation processes. This platform represents a significant advancement towards in-situ monitoring of yeast fermentation and the control of process parameters in large-scale bioreactors, with potential for diverse applications.

Date:11 Feb 2019 →  11 Oct 2023
Keywords:multi-sensor, biochip, bioreactor monitoring, yeast fermentation monitoring, electrochemical sensors, platinum nanostructures
Disciplines:Nanofabrication, growth and self assembly, Micro- and nanoelectromechanical systems, Semiconductor devices, nanoelectronics and technology
Project type:PhD project